Comparison, grouping, and preference

How does the attractiveness of a particular option depend on comparisons drawn between it and other alternatives? We observe that in many cases, comparisons hurt: When the options being compared have both meaningful advantages and meaningful disadvantages, comparison between options makes each option less attractive. The effects of comparison are crucial in choice problems involving grouped options, because the way in which options are grouped influences which comparisons are likely to be made. In particular we propose that grouping focuses comparison, making within-group comparisons moi-e likely than between-group comparisons. This line of reasoning suggests that grouping should hurt, and we observe that it does: An option is more likely to be chosen when alone than when part of a group.